Whistle



FIG. 1 is a front view of a whistle showing my new design;

FIG. 2 is a side view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a side view thereof;

FIG. 6 is a back view thereof; and,

FIG. 7 is a perspective view thereof. 

The ornamental design for a whistle, as shown. 